JPH057521B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a scroll-type fluid machine, and more particularly, a scroll-type fluid machine that includes a fixed scroll and a revolving scroll, and the revolving scroll is provided with a shaft portion that receives an eccentric shaft portion of a crankshaft. The present invention relates to a scroll type fluid machine in which the eccentric shaft portion is rotatably fitted into the shaft portion.

(Prior Art) In this type of fluid machine, a cam means is interposed between the shaft portion and the eccentric shaft portion, so that each of the above-mentioned A system in which the contact pressure acting between the laps of the scroll can be easily set to a desired value has already been proposed in Japanese Patent Laid-Open No. 129791/1983.

This will be briefly explained based on Fig. 7.
A shaft portion 52 for receiving an eccentric shaft portion 51 of a crankshaft (not shown) is provided on the back side of the revolving scroll 50,
A cam means 53 is interposed between the shaft portion 52 and the eccentric shaft portion 51, and the cam means 5
3, the axial center Or of the crankshaft, the axial center Oc of the eccentric shaft portion 51, and the axial center Os of the shaft portion 52.
As shown in Figure 7, the positional relationship with
and the line segment OsOr, and the included angle θ formed from the line segment OsOc in the rotational direction of the crankshaft is variable within the range of 90°<θ<180°. Scroll (not shown) and revolution scroll 50
The pressing force Fd that acts in the radial direction on the lap (not shown) of the revolving scroll 50 due to the internal pressure of the closed space (not shown) formed by the Of the pressing force caused by internal pressure, this is the component force in the direction perpendicular to the line segment OrOs.) is used to press the lap of the revolving scroll 50 against the lap of the fixed scroll, and apply an appropriate distance between these laps. The sealing force (contact pressing force) Fp was made to work. Specifically, the contact pressing force Fp is approximately given by Fp=Fd cotθ...a. For comparison with the present application, in the above relational expression, the revolving scroll 5
0 and the component force (pressing force) Fr in the direction perpendicular to the pressing force Fd among the pressing forces due to the internal pressure of the closed space, to derive a relational expression for calculating the contact pressing force Fp. Then, Fp=Fω−Fd cotθ−Fr …b. Further, ω in FIG. 7 indicates the rotation direction of the crankshaft.

(Problem to be solved by the present invention) However, in this case, when a compression action is performed in the closed space, the closed space sucks incompressible fluid (liquid compression), and the internal pressure of the closed space increases. death,
Accordingly, when the pressing force Fd increases, as is clear from the relational expression a above, the included angle θ
Since cotθ has a negative value in a range where the angle is greater than 90° and less than 180°, the contact pressing force Fp increases in proportion to the pressing force Fd. Therefore, in this conventional system, when the internal pressure of the closed space becomes abnormally high during liquid compression, the contact pushing force Fp also becomes too high, causing damage to the scrolls, such as seizure between the wraps of the scrolls. was occurring.

(Means for Solving the Problem) Accordingly, the present invention uses a cam means in the same way as in the prior art, and the axial center of the crankshaft, the axial center of the eccentric shaft portion, and the axial center of the shaft portion of the revolving scroll. The positional relationship between the fixed scroll and the revolving scroll has been devised in a way that is different from the conventional one, so that confining pressure can be automatically prevented from occurring during liquid compression. In a scroll type fluid machine, wherein the revolving scroll is provided with a shaft portion that receives an eccentric shaft portion of a crankshaft, and the eccentric shaft portion is rotatably engaged with the shaft portion, the axis Os of the shaft portion is While deviating from the axis Or of the crankshaft and the axis Oc of the eccentric shaft part,
A line segment connecting the crankshaft axis Or and the shaft axis Os is OsOr, a line segment connecting the shaft axis Os and the eccentric shaft axis Oc is OsOc, and these line segments OsOr , OSOc, and the included angle formed from the line segment OsOc in the rotational direction of the crankshaft is θ, then the included angle θ between the eccentric shaft portion and the shaft portion is, A cam means that is variable within the range O<cotθ is provided.

(Function) As described above, the centrifugal force acting on the revolving scroll due to the rotation of the crankshaft acts to press the lap of the scroll against the lap of the fixed scroll, while the rotation of the fixed scroll and the revolving scroll The pressing force acting on the wrap of the revolving scroll due to the internal pressure of the closed space (compression chamber) formed by the scroll acts to separate the scroll from the wrap of the fixed scroll. By setting the moment to be larger than the moment due to the pressing force, the wraps of the scrolls can be brought into contact with each other with an appropriate contact pressure, and at the same time, the incompressible fluid can not flow into the closed space. When liquid compression occurs and the internal pressure of the sealed space becomes abnormally high, the moment due to the pressing force caused by this internal pressure increases, causing the revolving scroll to move between the laps around the axis of the eccentric shaft portion. automatically pushed back in the direction of separation,
As a result, generation of confinement pressure in the closed space can be reliably prevented.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

The one shown in FIGS. 2 and 3 is one in which the present invention is applied to a compressor for a refrigeration system, in which a compression element 3 consisting of a fixed scroll 1 and a revolving scroll 2 is formed. A motor 4 for driving the compression element 3 is fixed to a frame 51 and installed inside the casing 5.

A cylindrical shaft portion 8 that pivotally supports an eccentric shaft portion 7 of a crankshaft 6 extending from the motor 4 is formed on the back side of the revolving scroll 2, and the eccentric shaft portion 7 is fitted onto the shaft portion 8. At the same time, a sliding body 9 is installed between the back side of the revolving scroll 2 and the frame A.
and a sliding body receiver 10, the scroll 2
An anti-rotation mechanism is provided to prevent rotation.

Further, a suction pipe 11 is connected to the casing 5 to lower the pressure inside the casing 5, and a suction port 12 provided in the compression element 3 is opened in the casing 5, while a discharge port 12 provided in the compression element 3 is opened in the casing 5. A discharge pipe 14 is connected to the port 13 so that the discharge port 13 is opened to the outside of the casing 5.

In this way, as the revolving scroll 2 revolves with respect to the fixed scroll 1 by driving of the motor 4, the compression element 3 sucks the low-pressure refrigerant from the suction port 12 and compresses the refrigerant, The high-pressure refrigerant is discharged to the outside of the casing 5 through the discharge pipe 14.

In FIG. 2, 15 and 16 are bearings for supporting the crankshaft 6 on the frame A, and 17 is a thrust bearing for supporting the revolving scroll 2 on the frame A in the thrust direction. be.

In the scroll type fluid machine configured as described above, as shown in FIGS. 2 and 3 and schematically shown in FIGS. 1 and 4, the shaft portion 8 and the eccentric shaft portion 7 of the crankshaft 6 are A cam ring (cam means) 71 is interposed in between, so that the axis Os of the shaft portion 8 is
It is deviated from the axis Or of the crankshaft 6 and the axis Oc of the eccentric shaft portion 7. Furthermore, 1
8 is a bearing metal.

Below, in specifically explaining this configuration, first, an evaporator and a condenser (none of which are shown) are connected to the fluid machine, and the fluid machine is operated steadily. The balance of the forces acting on the revolving scroll 2 and the moments of these forces with respect to the axis Oc of the eccentric shaft portion 7 will be explained.

The pressing force acting on the revolving scroll 2 is a first
To explain using a diagram, the force acting on the revolving scroll 2 is: - Fp is the contact pushing force that the revolving scroll 2 receives based on the contact pressure between the lap of the revolving scroll 2 and the lap of the fixed scroll 1; - Fw is the centrifugal force that acts on the revolving scroll 2 as the revolving scroll 2 rotates around the crankshaft 6, and Fr is the closed space (compression chamber) formed by the fixed scroll 1 and the revolving scroll 2. ) is the pressing force that acts on the revolving scroll 2 due to the internal pressure of the crankshaft 6, and is
・ Fd is the component force acting on the line connecting Or and the axis Os of the shaft portion 8 (hereinafter referred to as the first pressing force), Fd is the pressing force due to the internal pressure of the sealed space,
This is a component force in a direction perpendicular to the first pressing force Fr (hereinafter referred to as a second pressing force).

Therefore, on a virtual plane orthogonal to the axis Or of the crankshaft 6, the axis
A line segment OsOc connecting Os and the axis Oc of the eccentric shaft portion 7
and a line segment OsOr connecting the axis Os of the shaft portion 8 and the axis Or of the crankshaft 6, and an included angle formed from the line segment OsOc in the rotational direction of the crankshaft 6. When θ, the axis of the eccentric shaft portion 7 is
From the balance of moments centered on Oc, the following relationship holds true for the above-mentioned pushing force (pushing force): Fp=Fw−(Fdcotθ+Fr)…The centrifugal force Fw is the set rotation speed of the motor 4. Also, since the internal pressure of the sealed space is determined by the design load during normal operation, the first pressing force Fr and the second pressing force
Fd is also determined by the design load.
Under these conditions of the given pushing forces Fw, Fr, and Fd, the contact pressure Fp during normal operation can be easily set to the desired value by appropriately setting the included angle θ. .

Furthermore, if the included angle θ is set within a range where cotθ is positive, even if the closed space sucks liquid refrigerant and liquid compression occurs, the increase in the internal pressure of the space causes the 2 The pressing force Fd increases, and eventually,
When the contact pressure Fp becomes 0, a pressing force acts on the revolving scroll 2 in the direction of separating the laps of the scrolls 1 and 2. (The first pressing force Fr also acts on the revolving scroll 2 to separate the laps, but since the first pressing force Fr has a smaller effect than the second pressing force Fd, the following will be explained below. (The explanation will be omitted here.) Based on the above explanation, the cam ring 71 interposed between the eccentric shaft portion 7 and the shaft portion 8 allows the included angle θ to be set within the range where cotθ is positive. In addition, the contact pressure Fp is set to an appropriate value. In this example,
The included angle θ is set in a range greater than 0° and smaller than 90°, but as shown in FIG.
may be set to an angle greater than 180° and smaller than 270°.

The operation of the scroll type fluid machine constructed as above will be explained.

When the motor 4 is driven to cause the revolving scroll 2 to revolve at a desired rotation speed and the fluid machine is operated steadily, the centrifugal force is reduced as described above.
Since Fw, the first pressing force Fr, and the second pressing force Fd are all approximately constant during steady operation,
As is clear from the relationship of the above formula, the contact pressure Fp is determined to a desired value depending on the set included angle θ.

On the other hand, when the sealed space sucks liquid refrigerant and liquid compression occurs, the internal pressure of the sealed space increases and the second pressing force Fd increases significantly. However,
Since the included angle θ is set within a range where cotθ is positive, the contact pressure Fp decreases as the second pressing force Fd increases, and not only does it eventually reach 0, but the second The pressing force Fd causes the revolving scroll 2 to swing about the axis Oc of the eccentric shaft portion 7 in a direction in which the lap between the revolving scroll 2 and the fixed scroll 1 is separated. As a result, a gap is created between the wraps, and the sealed space is released to the low pressure side through this gap, thereby preventing the generation of confinement pressure.

In addition to the embodiment described above, the structure in which the cam means is interposed between the eccentric shaft part of the crankshaft and the shaft part is as shown in FIG.
The outer periphery of the crankshaft 6 is a cylindrical surface concentric with the axis Or of the crankshaft 6, and a receiving hole 72 is formed in the center of the eccentric shaft portion 7, while a receiving hole 72 protrudes into the receiving hole 72 on the back surface of the revolving scroll 2. forming a shaft portion 8,
A cam means (cam ring) 71 may be interposed between the eccentric shaft portion 7 and the shaft portion 8.

(Effects of the Invention) As described above, the cam means 71 is interposed between the eccentric shaft portion 7 and the shaft portion 8, and further, the included angle θ is controlled within a range where cotθ is positive. By setting the included angle θ appropriately in this range, the contact pressure Fp can be set to a desired value without increasing the machining accuracy of both scrolls 1 and 2. When the sealed space sucks incompressible fluid, the sealed space is automatically opened to the low pressure side to reliably prevent liquid compression. Damage to the scrolls 1 and 2 can also be reliably prevented.

[Brief explanation of the drawing]

Fig. 1 is a schematic plan view of an embodiment of the present invention, Fig. 2 is a vertical sectional view of the main part of the embodiment, Fig. 3 is a plan sectional view of the main part of the embodiment, and Fig. 4 is a schematic plan view of the main part of the embodiment. FIG. 5 is a schematic longitudinal sectional view of the example, FIG. 5 is a schematic explanatory diagram of another embodiment, FIG. 6 is a schematic longitudinal sectional diagram of another embodiment, and FIG. 7 is an explanatory diagram showing a conventional example. 1...Fixed scroll, 2...Revolving scroll, 6
...crankshaft, 7...eccentric shaft section, 8...shaft section, 71...
Cam means, θ...included angle.

Claims (1)

[Scope of Claims] 1. A fixed scroll 1 and a revolving scroll 2 are provided, the revolving scroll 2 is provided with a shaft portion 8 for receiving an eccentric shaft portion 7 of a crankshaft 6, and the eccentric shaft portion 7 is mounted on the shaft portion 8. In a scroll-type fluid machine that is fitted to rotate freely, the axial center Os of the shaft portion 8 is offset from the axial center Or of the crankshaft 6 and the axial center Oc of the eccentric shaft portion 7, and A line segment connecting the axis Or of the shaft 6 and the axis Os of the shaft 8 is OsOr, and the axis Os of the shaft 8 and the eccentric shaft 7
Let OsOc be the line segment connecting the axial center Oc of , the eccentric shaft portion 7 and the shaft portion 8
A scroll-type fluid machine characterized in that a cam means is interposed between the angle θ and the angle θ to make it variable within a range of O<cotθ.